This influence comes in two principal forms: through direct actions and the examples you set.

In his dimension, language (rather than matter and energy) is the principal form of physics.

Buses are the principal form of public transport within the city.

These legends were for long the principal form of literary entertainment enjoyed by the common people.

The principal form of public transport in the country is the shared taxi.

Since 1956, abortions have been the principal form of birth control in this country, and an estimated one million are performed each year.

The principal form of exercise in Grace was just getting from your house to wherever you needed to go.

A canto is the principal form of division in a long poem.

There are two principal forms of proactive search as outlined below.

There are two principal forms of search and I outline these below.